Topcon 50DX / color capture settings

Mon, 27 Jan 2025 21:44:19 GMT

Hi all,

We are fine-tuning the color capture settings on a new Topcon 50DX. Any suggestions for imaging optic nerve pallor, GA, blonde fundus etc? Even at 9 w/s (lowest flash output) these imaging scenarios are prone to overexposure and loss of detail. Where possible, we are moving the donut of light off axis to decrease the amount of light and then refocusing. However moving off axis isn't always an option.

Is there a neutral density filter available for the filter turret? Is there something we can adjust in the color sensor / capture config settings? Our color sensor is a Basler acA4112 (4096-3000). The color calibration looks good, however exposure is challenging with atrophy or nerve pallor etc.

Thank you in advance for any suggestions.

Steph

Mon, 27 Jan 2025 22:15:01 GMT

There are a lot of different ways to skin this cat.

If the sensor was a DSLR it would be easiest, however.

The second easiest way is software. What software are you running? Does that software allow you sensitivity control over the sensor?

There's usually an empty filter space on the 50DX, if it is empty you could use a neutral density filter. Some of those filters are available as a plastic film, if you can find it in that form they're easy to shape for a specific need and could help narrow down proof of concept, as well as what level of neutral density is ideal. The plastic film probably isn't the best long-term solution, but again could give a low cost proof of concept.

Fri, 31 Jan 2025 01:43:26 GMT

Thank you for your response, Paul. We are running IMAGENET 6. My colleague and I have tried a number of different settings in the capture config and dialed in a decent color calibration. This sensor is much more sensitive than our previous one, which is less flash output and better for patient comfort. Just presents its own challenges.

We also considered adding a neutral density to the filter turret. Maybe we will try that next.

Thanks!
Steph

Tue, 4 Feb 2025 14:07:24 GMT

I'd second the ND idea. It may be the easiest way to decrease the illumination but preserve the color balance you worked to perfect. It's amazing how a modest tweak in gain etc can throw everything out of balance. Let us know how it works out!

j-

Tue, 10 Jun 2025 22:18:55 GMT

We're in the process of a new creation. We're taking a Topcon NW8, and connecting a Canon R100 to it, and Kolari Vision has a "drop-in-filter" system that takes the mirrorless R100 back to the EF/EFS lens mount, putting its focal plane back to where it needs to be in order to work with the Topcon NW8. I'm working with Integrated Ophthalmic to get a PC with OVision that'll work with the NW8. We should have a lot more quick-easy filter changes available to us with the new setup. Maybe we'll find something interesting from the new capabilities.

Oh, and the drop-in filter mount gives the option to use a variable ND filter.